1. Field of the Invention
The present invention relates to a voltage-dividing resistor in a semiconductor device. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for implementing voltage drops of various sizes using a plurality of resistors of differing size.
2. Discussion of the Related Art
Referring to FIG. 1, a voltage-dividing resistor according to a related art consists of a semiconductor substrate 100, an oxide layer 110 formed on the semiconductor substrate 100, a polysilicon layer 140 formed on the oxide layer 110 to have internal resistance, an insulating layer 130 covering the polysilicon layer 140, an electrode 160 receiving a first reference voltage, an electrode 170 receiving a second reference voltage, and a plurality of electrodes 181, 183, 185, and 187.
The first reference voltage, e.g., a ground potential, is applied to the electrode 160. The second reference voltage, e.g., a voltage level Vdd, is applied to the electrode 170. Hence, the ground potential is applied to one end of the polysilicon layer 140 contacting the electrode 160 via a contact hole, and the voltage level Vdd is applied to the other end of the polysilicon layer 140 contacting the electrode 170 via a contact hole. A voltage drop amounting to the voltage level Vdd is generated by the internal resistance of the polysilicon. Moreover, a tungsten silicide layer 150 can be formed on the polysilicon layer 140 contacting the electrodes 160 and 170 via the respective contact holes to reduce contact resistance.
The electrodes 181, 183, 185, and 187 are arranged between the electrodes 160 and 170 to leave an equal distance d between adjacent electrodes, to thereby divide the voltage level Vdd for each equal distance by a correspondingly equal division of the inner resistance of the polysilicon layer 140. In particular, the electrode 181 outputs a voltage of 1/5 Vdd, the electrode 183 outputs a voltage of 2/5 Vdd, the electrode 185 outputs a voltage of 3/5 Vdd, and the electrode 187 outputs a voltage of 4/5 Vdd.
In the above-configured voltage-dividing resistor, as the electrodes 181, 183, 185, and 187 are arranged equidistantly, the internal resistance of the polysilicon layer is equally divided with the equal distance, so that a voltage drop of the corresponding value can be realized and implemented in a circuit. Therefore, the related art voltage-dividing resistor enables the voltage drop of predetermined steps only and cannot be adaptively applied.